Process for realizing a system for recovering heat, in particular based on the Seebeck&#39;s effect, and corresponding system

ABSTRACT

An embodiment of a process for realizing a system for recovering heat is described, the process comprising the steps of: formation on a substrate of a plurality of L-shaped down metal structures; deposition of a dielectric layer on the substrate and the plurality of L-shaped down metal structures by using a screen printing approach; definition and opening in the dielectric layer of upper contacts and lower contacts of the L-shaped down metal structures; formation of a plurality of L-shaped up metal structures being connected to the plurality of L-shaped down metal structure in correspondence of the upper and lower contacts so as to form a plurality of serially connected thermocouples, each comprising at least one L-shaped down metal structure and at least one L-shaped up metal structure, being made of different metal materials and interconnected at a junction, the serially connected thermocouples thus realizing the system for recovering heat.

PRIORITY CLAIM

The instant application claims priority to Italian Patent ApplicationNo. MI2009A002313, filed Dec. 28, 2009, which application isincorporated herein by reference in its entirety.

TECHNICAL FIELD

An embodiment relates to a process for realizing a system for recoveringheat.

An embodiment also relates to a system for recovering heat.

An embodiment particularly, but not exclusively, relates to a processfor realizing a system for recovering heat, in particular based on theSeebeck's effect and comprising a plurality of thermocouples and thefollowing description is made with reference to this field ofapplication for convenience of explanation only.

BACKGROUND

As it is well known, in the continuous research aimed to maximize theutilization of the electric power which is employed for normal humanactivities, the recovery of the heat, being produced as a secondaryeffect in these activities, is one of the keypoints to optimize theenergy rendering and also to reduce the total power consumption in anykind of apparatus.

For this reason, several systems have been studied over the years,usually indicated as “scavengers”, which are able to recover the heatgenerated by an operation performed by using electric energy.

Many known solutions, unfortunately, have a low efficiency value (for amaximum of around 10%), calculated as the amount of recovered heat,taking into account of the overall quantity of available heat.

It has been observed that solutions based on the Seebeck's effect aretypically more efficient in term of energy balance because they allow aone-way and direct transformation of the heat into electric power.

The Seebeck's effect is in fact a thermoelectric effect providing adirect conversion of temperature differences into an electric voltage.

In particular, since metals respond differently to temperature, it ispossible to create a current loop, when a closed loop is formed of twometals being joined and having opposite ends in two places with atemperature difference. In fact, a voltage is created in the presence ofa temperature difference between two different metals or semiconductors,a continuous current then flowing in the conductors if they form acomplete loop.

The Seebeck's effect is commonly used in a device called thermocouple(because it is made from a coupling or junction of materials, usuallymetals) to directly measure a temperature difference or to measure anabsolute temperature by setting one of its ends to a known temperature.

A thermocouple based on the Seebeck's effect may be also used, workingin an opposite way, for the production of electrical power by convertinga gradient of temperatures into electricity, thus being an efficientsystem for recovering heat, as above indicated.

Also efficient systems based on the Seebeck's effect are, however, boundby the underlying physical principle which is linked to thephysical-chemical nature of the materials being used to form thethermocouple, and also depends on the difference of temperatures betweenthe thermocouple ends, such that the problem of a low efficiency mayalso arise in these systems.

SUMMARY

An embodiment is a process for realizing a system for recovering heatbased on the Seebeck's effect having structural and functionalcharacteristics which allow optimizing and to increasing theirefficiency by maximizing the use of a thermal gradient and, at a sametime, reducing the resistance of the system so obtained, which has thusan improved rendering, in this way overcoming the limits which stillaffect systems realized according to the prior art.

An embodiment maximizes the areas capable of picking up the availableheat of a system for recovering heat by using a serial connection of ahigh number of devices for recovering heat, in particular thermocouples.It may be observed that an embodiment of a system comprising theserially connected thermocouples may also have a reduced transmission ofheat in the corresponding junctions.

An embodiment of a process for realizing a system for recovering heatcomprises the steps of:

-   -   formation on a substrate of a plurality of L-shaped down metal        structures;    -   deposition of a dielectric layer on said substrate and said        plurality of L-shaped down metal structures by using a screen        printing approach;    -   definition and opening in said dielectric layer of upper        contacts and lower contacts of said L-shaped down metal        structures; and    -   formation of a plurality of L-shaped up metal structures being        connected to said plurality of L-shaped down metal structure in        correspondence of said upper and lower contacts        so as to form a plurality of serially connected thermocouples,        each comprising at least one L-shaped down metal structure and        at least one L-shaped up metal structure, being made of        different metal materials and interconnected at a junction, said        serially connected thermocouples thus realizing said system for        recovering heat.

More in particular, an embodiment may comprise the followingsupplemental and optional features, taken alone or in combination whenneeded.

According to an embodiment, said step of deposition of a dielectriclayer by using a screen printing approach is performed on a substrate,being made of on a material chosen between silicon, ceramics, glass,plastic, and the like.

According to an embodiment, said step of deposition of said dielectriclayer comprises a step of depositing dielectric paste formed by means ofmaterials having a low electrical and thermal conductivity.

In particular, yet according to an embodiment, said step of depositionof said dielectric layer comprises a step of depositing a dielectriclayer having resistance value greater than approximately 10 GΩ/sq/mil,for example between approximately 10 and 20 GΩ/sq/mil and a thermalcoefficient smaller that approximately 1.25 W/(mK), for example betweenapproximately 1.04 W/(mK) and 1.25 W/(mK).

Further according to an embodiment, said step of deposition of saiddielectric layer comprises a step of depositing of approximately 50-100μm, for example approximately 100 μm.

Moreover, according to an embodiment, said step of formation of saidL-shaped down metal structures comprises a step of deposition anddefinition of a first metal layer on said substrate.

According to an embodiment, said step of formation of said L-shaped upmetal structures further comprises a step of deposition and definitionof a second metal layer, being different from said first metal layer.

Moreover, according to an embodiment, said step of deposition anddefinition of said first metal layer on said substrate comprises thesteps of:

-   -   patterning of said first metal layer by using a first        photoresist layer and a photolithographic technique to realize        first and second islands of said first metal layer on said        substrate being suitably separated from one another;    -   deposition of a second photoresist layer and subsequent        patterning by using a photolithographic technique, said second        photoresist layer covering only partially said first and second        islands and an entire portion of said substrate being left        exposed between such islands; and    -   removal of said second photoresist layer with the formation of        said first and a second down metal structure on said substrate,        being L-shaped and separate by a gap in correspondence with said        portion of said substrate being left exposed between said first        and second islands.

According to another embodiment, said step of definition and opening insaid dielectric layer of upper contacts and lower contacts comprises thesteps of:

-   -   deposition of a third photoresist layer on said dielectric        layer,    -   patterning of said third photoresist layer, defining therein a        plurality of openings in correspondence of upper ends of said        L-shaped down metal structures;    -   etching and removal of said third photoresist layer, thus        defining said upper contacts;    -   deposition of a fourth photoresist layer, also inside said upper        contacts;    -   patterning of said fourth photoresist layer defining a further        plurality of openings in correspondence of lower ends of said        L-shaped down metal structures; and    -   etching and removal of said fourth photoresist layer, thus        defining said lower contacts.

In particular, according to an embodiment, said step of etching andremoval of said fourth photoresist layer also defines first and secondinternal dielectric portions and first and second external dielectricportions of said dielectric layer, said first internal dielectricportion being positioned on a first down metal structure and in contactwith a first L-shaped up metal structure, said first external dielectricportion being positioned between said first L-shaped up metal structureand said substrate and in contact with said first down metal structureas well as to a second down metal structure, said second internaldielectric portion being positioned on said second down metal structureand in contact with said first L-shaped up metal structure as well witha second L-shaped up metal structure, and said second externaldielectric portion being positioned between said second L-shaped upmetal structure and said substrate and in contact with said second downmetal structure.

According to yet another embodiment, said step of formation of saidL-shaped up metal structures comprises the steps of.

-   -   deposition of said second metal layer on said dielectric layer        and within said upper and lower contacts;    -   patterning of said second metal layer by using a fifth        photoresist layer and a photolithographic technique;    -   etching and removal of said fifth photoresist layer, thus        defining said L-shaped up metal structures, being connected to        said L-shaped down metal structures.

According to an embodiment, said step of formation of said L-shaped upmetal structures forms said L-shaped up metal structures in such a waythat a lower end of a first L-shaped up metal structure is connected toa corresponding lower end of a first down metal structure and an upperend of said first L-shaped up metal structure is connected to an upperend of a second down metal structure, in turn having a lower endconnected to a lower end of a second L-shaped up metal structure.

In particular, according to an embodiment, said step of formation ofsaid L-shaped down metal structures comprises a step of deposition ofaluminium as said first metal layer.

Moreover, according to an embodiment, said step of formation of saidL-shaped up metal structures comprises a step of deposition of gold assaid second metal layer.

An embodiment also includes a system for recovering heat of the typecomprising a plurality of thermocouples, each comprising an L-shapeddown metal structure and an L-shaped up metal structure beinginterconnected in correspondence of a first junction, wherein saidthermocouples are realized on a substrate by using a first and a secondmetal and connected in a serial mode covering a wide area of saidsubstrate in a serpentine-like geometry by using an embodiment of aprocess as previously described.

According to an embodiment, said substrate is made on a material chosenbetween silicon, ceramics, glass, plastic and the like.

According to an embodiment, said L-shaped down and up metal structuresof each of said thermocouples are orthogonal to each other.

According to an embodiment, said L-shaped down and up metal structuresof each of said thermocouples are in line with each other.

Furthermore, according to an embodiment, said thermocouples aredimensioned to minimize their contact resistance, the resistivity of theL-shaped down and up metal structures and the thermal conductivity ofthe thermocouples as a whole.

In particular, according to an embodiment, said L-shaped metal downstructure have a length between approximately 200 and 800 μm, forexample approximately 600 μm, a width between approximately 100 and 200μm, for example approximately 150 μm and a thickness betweenapproximately 25 and 50 μm, for example approximately 50 μm, and saidL-shaped metal up structure have a length between approximately 50 and150 μm, for example approximately 100 μm, a width between approximately50 and 150 μm, for example approximately 100 μm and a thickness betweenapproximately 50 and 100 μm, for example approximately 100 μm.

According to an embodiment, said L-shaped down metal structures of saidthermocouples are made on aluminium.

According to an embodiment, said L-shaped up metal structures of saidthermocouples are made on gold.

BRIEF DESCRIPTION OF THE DRAWINGS

Characteristics and advantages of a process and of a system forrecovering heat according to the invention will be apparent from thefollowing description of one or more embodiments thereof given by way ofindicative and non-limiting example with reference to the annexeddrawings.

In such drawings:

FIGS. 1A-1I schematically show the different steps of a process forrealizing a system for recovering heat according to an embodiment;

FIG. 2 schematically shows a three-dimensional view of a device forrecovering heat, in particular a single thermocouple, of a systemaccording to an embodiment as obtained by an embodiment of the processof FIGS. 1A-1I;

FIGS. 3A and 3B schematically show a schematic layout view and anenlarged view of an embodiment of a system for recovering heat asobtained by an embodiment of the process of FIGS. 1A-1I; and

FIGS. 4A and 4B schematically show a schematic layout view and anenlarged view of another embodiment of a system for recovering heat asobtained by an embodiment of the process of FIGS. 1A-1I.

DETAILED DESCRIPTION

With reference to such figures, and in particular to FIGS. from 1A to1I, in the following lines an embodiment of a process for realizing asystem 15 for recovering heat will be described.

It is noted that the process steps being described hereinafter may notbe for a complete manufacturing process of an integrated circuit. Anembodiment may be carried out along with the manufacturing techniques ofintegrated circuits being usually employed in the field, and only thoseprocess steps being necessary to comprise an embodiment may bedescribed.

Moreover, figures showing schematic views of integrated circuit portionsduring the manufacturing may not be drawn to scale, being on thecontrary drafted so as to emphasise important features of one or moreembodiments.

An embodiment starts from a goal of improving or optimizing theefficiency of a system for recovering heat, in particular based on theSeebeck's effect, by using the available heat energy, and thus bywidening the areas being capable of picking up the available heat.

As will be clear from the following the description, an embodiment of aproposed process for realizing a system for recovering heat, inparticular based on the Seebeck's effect, may allow overcoming two maindifficulties being encountered:

-   -   a) realizing large contact areas of the metal junctions of an        employed thermocouple to obtain a lower-resistance thermal        transmission in the junctions themselves to increase the speed        at which a temperature difference develops in the thermocouple        ends, and thus to obtain a consequent fast reaching of an        undesired thermal balance;    -   b) on the contrary, reducing the contact areas of the        thermocouple metal junctions would increase their contact        resistance with a consequent equally undesired potential loss        due to the Joule effect.

As will be clarified by the following description, an embodimentarranges different conventional and innovative techniques for realizingon a wide area a system 15 for recovering heat by producing electricalpower based on the Seebeck's effect. According to an embodiment, aserial connection of a high number of single devices 10 for recoveringheat, in particular thermocouples, is realized in order to optimise theheat recovering and to reduce, at the same time, the heat transmissionin the metal junctions realizing such thermocouples.

In particular, with reference to the FIGS. 1A to 1I, an embodiment of aprocess for realizing a system 15 for recovering heat, in particularbased on the Seebeck's effect, comprises the steps of:

-   -   deposition on a substrate 1 of a first metal layer 2, in        particular an aluminium layer and subsequent patterning of the        first metal layer 2 by using a first photoresist layer 3 and a        photolithographic technique, as shown in FIG. 1A; after the        photolithography, a first 2′ and a second island 2″ of the first        metal layer 2 are obtained, being suitably separated one another    -   deposition of a second photoresist layer 4 and subsequent        patterning by using a photolithographic technique, the second        photoresist layer 4 covering only partially the first and second        islands, 2′ and 2″, of the first metal layer 2 and the entire        portion of the substrate 1 being left exposed between such        islands, as shown in FIG. 1B;    -   removal of the second photoresist layer 4 with the formation of        a first 2A and a second down metal structure 2B on the substrate        1, such down metal structures 2A and 2B being L-shaped and        separate by a gap 4A in correspondence with the portion of the        substrate 1 being left exposed between the islands 2′ and 2″ of        the first metal layer 2, as shown in FIG. 1C;    -   deposition of a dielectric layer 5, in particular a dielectric        paste, on the first and second down metal structures, 2A and 2B,        as well on the substrate 1 being left exposed outside said        structures, for instance in correspondence of the gap 4, by        using a screen printing approach, followed by a deposition of a        third photoresist layer 6, being thus patterned defining therein        a plurality of openings, 6A, 6B in correspondence of upper ends        of the L-shaped down metal structures 2A and 2B, as shown in        FIG. 1D;    -   etching and removal of the third photoresist layer 6, thus        defining a first 7A and a second upper contact 7B of the first        and second L-shaped down metal structures, 2A and 2B,        respectively, as shown in FIG. 1E;    -   deposition of a fourth photoresist layer 8, also inside the        first and second upper contacts, 7A and 7B, being thus patterned        in order to define a further plurality of openings, 8A, 8B in        correspondence of lower ends of the L-shaped down metal        structures, 2A and 2B, as shown in FIG. 1F;    -   etching and removal of the fourth photoresist layer 8, thus        defining a first 9A and a second lower contact 9B of the first        and second L-shaped down metal structures 2A and 2B,        respectively, as well as a first 13A and a second internal        dielectric portion 13B and a first 14A and second external        dielectric portion 14B of said dielectric layer 5, as shown in        FIG. 1G;    -   deposition of a second metal layer 12, being different from the        first metal layer 2, in particular a gold layer, and subsequent        patterning of the second metal layer 12 by using a fifth        photoresist layer 11 and a photolithographic technique, as shown        in FIG. 1H;    -   etching and removal of the fifth photoresist layer 11, thus        defining a first 12A and a second L-shaped up metal structure        126, being connected to the first and second L-shaped down metal        structures 2A and 2B in such a way to form respective metal        loops, as shown in FIG. 1I.

In an embodiment, the deposition of a dielectric layer 5 by using ascreen printing approach may allow one to use any kind of substrate 1,being made of on a material chosen between silicon, ceramics, glass,plastic and the like, for example silicon.

In particular, the screen printing approach is derived from anembodiment of a printing technique that uses a woven mesh to support anink-blocking stencil forming open areas of mesh that transfer ink as asharp-edged image onto a substrate. In the electronic circuitmanufacturing field, the screen printing comprises a transfer of a pasteonto a substrate by extrusion through a patterned screen mesh.

Using a screen printing approach makes the process more versatile than atraditional one since the surface may not have to be printed underpressure, unlike etching or lithography, and it may not have to beplanar, offering capabilities that may not be achievable by wet chemicaland photolithographic methods.

As a result of the above steps sequence, an embodiment allows obtaininga plurality of devices for recovering heat, in particular thermocouples10 comprising an L-shaped down metal structure and an L-shaped up metalstructure.

In particular, the lower end of the first L-shaped up metal structure12A is connect to a corresponding lower end of the first down metalstructure 2A, while the upper end of the first L-shaped up metalstructure 12A is connected to the upper end of the second down metalstructure 2B, in turn having the lower end connected to the lower end ofthe second L-shaped up metal structure 12B.

Moreover, the first internal dielectric portion 13A is positioned on thefirst down metal structure 2A and in contact with the first L-shaped upmetal structure 12A while the first external dielectric portion 14A ispositioned between the first L-shaped up metal structure 12A and thesubstrate 1 and in contact with the first down metal structure 2A aswell as to the second down metal structure 2B.

In a similar way, the second internal dielectric portion 13B ispositioned on the second down metal structure 2B and in contact with thefirst L-shaped up metal structure 12A as well with the second L-shapedup metal structure 12B while the second external dielectric portion 14Bis positioned between the second L-shaped up metal structure 12B and thesubstrate 1 and in contact with the second down metal structure 2B.

It is noted that the relative terms “up”, “down”, “upper”, and “lower”have been used considering the substrate 1 as a base level of the system15 for recovering heat and the development direction of the multilayerstructure above the substrate 1 as increasing from the substrate. Thedown metal structures 2A and 2B are thus closer to the substrate 1 withrespect to the L-shaped up metal structures 12A and 12B.

In its most general terms, an embodiment comprises the following steps:

-   -   formation on a substrate 1 of a plurality of L-shaped down metal        structures 2A, 2B;    -   deposition of a dielectric layer 5 on the substrate 1 and the        plurality of L-shaped down metal structures 2A, 2B, by using a        screen printing approach;    -   definition and opening in the dielectric layer 5 of upper        contacts 7A, 7B and lower contacts 9A, 9B of the L-shaped down        metal structures, 2A, 2B    -   formation of a plurality of L-shaped up metal structures 12A,        12B being connected to the plurality of L-shaped down metal        structure 2A, 2B in correspondence of the upper and lower        contacts, 7A, 7B and 9A, 9B.

In particular, the step of formation of the L-shaped down metalstructures 2A and 2B comprises a step of deposition and definition ofthe first metal layer 2 (also indicated as first metal level).

Moreover, in an embodiment, the step of deposition of a dielectric layer5 is proceeded by a step of removal of the first resist layer 3.

Also, the dielectric layer 5 may be realized by a dielectric pasteformed by means of materials having a low electrical and thermalconductivity, i.e. a high resistance and a low thermal coefficient. Inan embodiment, the dielectric layer 5 has resistance value greater than10 GΩ/sq/mil, for example between 10 and 20 GΩ/sq/mil, and a thermalcoefficient smaller than 1.25 W/(mK), for example between 1.04 W/(mK)and 1.25 W/(mK). Suitable materials for the dielectric layer 5 includeUV curable pastes, such as the 5018 UV curable paste by DuPont.

Finally, in an embodiment, the step of formation of the L-shaped upmetal structures 12A and 12B comprises a step of deposition anddefinition of the second metal layer 12 (also indicated as second metallevel).

In this way, the plurality of devices for recovering heat, in particularthermocouples 10 being thus formed are interconnected in a serial modein order to realize an embodiment of the system 15 for recovering heat.

An embodiment of a device for recovering heat, in particular anembodiment of a thermocouple 10 so obtained is shown in FIG. 2 in a 3-Dview.

In particular, the thermocouple 10 comprises an L-shaped down metalstructure 2 and an L-shaped up metal structure 12, being interconnectedin correspondence of a first junction 10A. Moreover, the L-shaped downmetal structure 2 is also connected to an L-shaped metal up structure ofa previous thermocouple in the system 15, while the L-shaped up metalstructure 12 is also connected to a L-shaped metal down structure of afollowing thermocouple in the system 15, the relative terms “previous”and “following” having been used with reference to the representation ofthe FIG. 2 L-shaped down metal structure 2.

The thermocouple 10, during its operate, has the metal structures 2 and12 at different temperatures, T1 and T2 in FIG. 2, a difference beingset between these temperatures (for instance, T1<T2 as indicated in FIG.2).

According to an embodiment, the system 15 for recovering heat comprisesseveral thermocouples 10 connected in a serial mode. In particular, thesystem 15 for recovering heat so obtained is able to produce electricpower when a difference of temperature is established between itssurface and its back side, i.e. between the L-shaped down metalstructures 2 and the L-shaped up metal structures 12 forming theirserially connected thermocouples 10.

In an embodiment the serially connected thermocouples 10 may be realizedin order to cover a wide area of the substrate 1, so as to improve theefficiency of the system 15 for recovering heat as a whole.

FIGS. 3A and 4A show respective embodiments of serially connectedthermocouples 10 of the system 15 for recovering heat.

More in detail, as shown in FIG. 3A, according to an embodiment of thesystem 15 for recovering heat, the serially connected thermocouples 10are aligned in a serpentine manner, the L-shaped down and up metalstructures, 2 and 12, being orthogonal to each other, as shown in theenlarged view of FIG. 3B.

According to another embodiment of the system 15 for recovering heat asshown in FIG. 4A, the serially connected thermocouples 10 are alsoaligned in a serpentine manner, the L-shaped down and up metalstructures, 2 and 12, being, however, in line with each other, as shownin the enlarged view of FIG. 4B.

It is noted that the design of an embodiment of a system for recoveringheat may be realized by taking into account the overall resistivity andthe different contributions in terms of thermal management.

In particular, a serpentine-like geometry of the system 15 forrecovering heat has been used to provide a wide area system and thesingle thermocouples 10 are dimensioned to minimize their contactresistance as well as the resistivity of the tracks of metal (the firstand second metal levels) and the thermal conductivity of thethermocouples themselves. In particular, the L-shaped metal downstructures 2 have a length between approximately 200 and 800 μm, forexample approximately 600 μm, a width between approximately 100 and 200μm, for example approximately 150 μm and a thickness betweenapproximately 25 and 50 μm, for example approximately 50 μm, while theL-shaped metal up structures 12 have a length between approximately 50and 150 μm, for example approximately 100 μm, a width betweenapproximately 50 and 150 μm, for example approximately 100 μm and athickness between approximately 50 and 100 μm, for example approximately100 μm.

In summary, an embodiment allows obtaining a system for recovering heatcomprising a plurality of thermocouples being serially connected andrealized on a wide area and being able to convert a difference oftemperature in to electrical power, the system 15 for recovering heatbeing formed on any kind of substrate 1.

In particular, the system 15 for recovering heat according to anembodiment may be realized on substrates made of different materials (asceramics, glass, plastic, etc.) as well as on a conventional siliconsubstrate. In this latter case, the traditional techniques ofmanufacturing microelectronic devices may be used.

Also according to an embodiment, a mix and match of different processesdue to the different materials being used may give the possibility ofhaving a large flexibility and versatility of the process, in particularallowing the realize of an embodiment of the system 15 for recoveringheat also from unconventional materials, the serpentine-like geometryproviding a wide area system.

Moreover, the design of an embodiment of a system for recovering heat isrealized taking into account the overall resistivity and the differentcontributions in terms of thermal management, the single thermocouplesbeing dimensioned so as to minimize their contact resistance as well asthe resistivity of the tracks of metal and the thermal conductivity ofthe thermocouples themselves.

To this end, a dielectric layer may be realized by a dielectric pasteformed by means of materials having a low electrical and thermalconductivity.

Finally, in an embodiment, the serially connected thermocouples on awide area provides for an optimum use of the available heat, the systemfor recovering heat being thus an efficient system using the heatproduced by different sources (being thus at different temperatures), toproduce electric power.

The process according to an embodiment may be also used to producematerial for the building (e.g., of tiles) to use in environmentswherein temperature gradients are present.

An embodiment of such a thermocouple may be disposed on an integratedcircuit that is coupled to another integrated circuit, e.g., aprocessor, to form a system.

Furthermore, an embodiment of such a thermocouple may be included inbuilding materials or components (e.g., title), across which atemperature differential may exist.

From the foregoing it will be appreciated that, although specificembodiments have been described herein for purposes of illustration,various modifications may be made without deviating from the spirit andscope of the disclosure. Furthermore, where an alternative is disclosedfor a particular embodiment, this alternative may also apply to otherembodiments even if not specifically stated.

The invention claimed is:
 1. An apparatus, comprising: a substratehaving an upper surface; an L-shaped first monolithic metal member,having first and second ends, and configured to have a firsttemperature, the second end of the L-shaped first monolithic metalmember being at a longer side of the L-shaped first monolithic metalmember and the longer side positioned directly on the upper surface ofthe substrate; an L-shaped third monolithic metal member positioneddirectly on the upper surface of the substrate and having first andsecond ends; and an L-shaped second monolithic metal member disposedover the L-shaped first monolithic metal member and the L-shaped thirdmonolithic metal member, having a first end electrically coupled to anupper surface of the second end of the L-shaped first monolithic metalmember, having a second end electrically coupled to an upper surface ofthe first end of the L-shaped third monolithic metal member, andconfigured to have a second temperature and to conduct a current fromthe L-shaped first monolithic metal member in response to a nonzerodifference between the first and second temperatures.
 2. The apparatusof claim 1 wherein the first end of the L-shaped third monolithic metalmember extends up toward the L-shaped second monolithic metal member. 3.The apparatus of claim 1 wherein the first end of the L-shaped secondmonolithic metal member extends down toward the L-shaped firstmonolithic metal member.
 4. The apparatus of claim 1 wherein the firstend of the L-shaped second monolithic metal member being at a shorterside of the L-shaped second monolithic metal member, and the second endof the L-shaped second monolithic metal member being at a longer side ofthe second monolithic metal member.
 5. The apparatus of claim 1 wherein:the L-shaped first monolithic metal member comprises a first metal; andthe L-shaped second monolithic metal member comprises a second metal. 6.The apparatus of claim 1 wherein: one of the L-shaped first and secondmonolithic metal members comprises gold; and the other of the L-shapedfirst and second monolithic metal members comprises aluminium.
 7. Theapparatus of claim 1 wherein the second end of the L-shaped firstmonolithic metal member is in contact with the first end of the L-shapedsecond monolithic metal member.
 8. The apparatus of claim 1 wherein eachof the L-shaped first and second monolithic metal members comprise highelectrical conductivity and a relatively low thermal conductivity. 9.The apparatus of claim 1, further comprising: a first dielectric regiondisposed over the L-shaped first monolithic metal member and adjacent tothe L-shaped second monolithic metal member; and a second dielectricregion disposed under the L-shaped second monolithic metal member andadjacent to the L-shaped first monolithic metal member.
 10. Theapparatus of claim 1, further comprising: a first dielectric regiondisposed over the L-shaped first monolithic metal member, adjacent tothe L-shaped second monolithic metal member, and having a low thermalconductivity; and a second dielectric region disposed under the L-shapedsecond monolithic metal member, adjacent to the L-shaped firstmonolithic metal member, and having a relatively low thermalconductivity.
 11. The apparatus of claim 1, further comprising: a firstdielectric region disposed over the L-shaped first monolithic metalmember, adjacent to the L-shaped second monolithic metal member, andhaving a low thermal conductivity; and a second dielectric regiondisposed under the L-shaped second monolithic metal member, adjacent tothe L-shaped first monolithic metal member, having a low thermalconductivity, and including a same material as the first dielectricregion.
 12. The apparatus of claim 1 wherein the L-shaped secondmonolithic metal member is angled relative to the L-shaped firstmonolithic metal member.
 13. The apparatus of claim 1 wherein theL-shaped second monolithic metal member is perpendicular to the L-shapedfirst monolithic metal member.
 14. A system, comprising: a firstintegrated circuit, comprising: a substrate having an upper surface; anL-shaped first monolithic metal member positioned on the upper surfaceof the substrate, having first and second ends, and configured to have afirst temperature, the second end of the L-shaped first monolithic metalmember being at a longer side of the L-shaped first monolithic metalmember and the longer side positioned directly on the upper surface ofthe substrate; an L-shaped third monolithic metal member positioneddirectly on the upper surface of the substrate and having first andsecond ends; and a second monolithic metal member disposed over theL-shaped first monolithic metal member and the L-shaped third monolithicmetal member, having a first end electrically coupled to an uppersurface of the second end of the L-shaped first monolithic metal member,having a second end electrically coupled to an upper surface of thefirst end of the L-shaped third monolithic metal member, and configuredto have a second temperature and to conduct a current from the L-shapedfirst monolithic metal member in response to a nonzero differencebetween the first and second temperatures; and a second integratedcircuit coupled to the first integrated circuit.
 15. The system of claim14 wherein the first and second integrated circuits are disposed on asame integrated-circuit die.
 16. The system of claim 14 wherein thefirst and second integrated circuits are disposed on respectiveintegrated-circuit dies.
 17. The system of claim 14 wherein one of theL-shaped first and second circuits comprises a processor.
 18. Abuilding, comprising: a component, comprising: a substrate having anupper surface; an L-shaped first monolithic metal member positioned onthe upper surface of the substrate, having first and second ends, andconfigured to have a first temperature, the second end of the L-shapedfirst monolithic metal member being at a longer side of the L-shapedfirst monolithic metal member and the longer side positioned directly onthe upper surface of the substrate; an L-shaped third monolithic metalmember positioned directly on the upper surface of the substrate andhaving first and second ends; and a second monolithic metal memberdisposed over the L-shaped first monolithic metal member and theL-shaped third monolithic metal member, having a first end electricallycoupled to an upper surface of the second end of the L-shaped firstmonolithic metal member, having a second end electrically coupled to anupper surface of the first end of the L-shaped third monolithic metalmember, and configured to have a second temperature and to conduct acurrent from the L-shaped first monolithic metal member in response to anonzero difference between the first and second temperatures.
 19. Thebuilding of claim 18 wherein the component comprises a tile.
 20. Thebuilding of claim 18 wherein the component comprises a window.
 21. Thebuilding of claim 18 wherein the component comprises a wall.
 22. Thebuilding of claim 18 wherein the component comprises a floor.